This invention relates to thermal transfer elements and methods of transferring layers to form devices on a receptor. In particular, the invention relates to a thermal transfer element having a multicomponent transfer unit and methods of using the thermal transfer element for forming a device, such as an optical or electronic device, on a receptor.
Many miniature electronic and optical devices are formed using layers of different materials stacked on each other. These layers are often patterned to produce the devices. Examples of such devices include optical displays in which each pixel is formed in a patterned array, optical waveguide structures for telecommunication devices, and metal-insulator-metal stacks for semiconductor-based devices.
A conventional method for making these devices includes forming one or more layers on a receptor substrate and patterning the layers simultaneously or sequentially to form the device. In many cases, multiple deposition and patterning steps are required to prepare the ultimate device structure. For example, the preparation of optical displays may require the separate formation of red, green, and blue pixels. Although some layers may be commonly deposited for each of these types of pixels, at least some layers must be separately formed and often separately patterned. Patterning of the layers is often performed by photolithographic techniques that include, for example, covering a layer with a photoresist, patterning the photoresist using a mask, removing a portion of the photoresist to expose the underlying layer according to the pattern, and then etching the exposed layer.
In some applications, it may be difficult or impractical to produce devices using conventional photolithographic patterning. For example, the number of patterning steps may be too large for practical manufacture of the device. In addition, wet processing steps in conventional photolithographic patterning may adversely affect integrity, interfacial characteristics, and/or electrical or optical properties of the previously deposited layers. It is conceivable that many potentially advantageous device constructions, designs, layouts, and materials are impractical because of the limitations of conventional photolithographic patterning. There is a need for new methods of forming these devices with a reduced number of processing steps, particularly wet processing steps. In at least some instances, this may allow for the construction of devices with more reliability and more complexity.
Generally, the present invention relates to thermal transfer elements and methods of using thermal transfer elements for forming devices, including optical and electronic devices. One embodiment is a thermal transfer element that includes a substrate and a multicomponent transfer unit that, when transferred to a receptor, is configured and arranged to form at least a first operational layer and a second operational layer of a multilayer device. The first operational layer is configured and arranged to conduct or produce a charge carrier or to produce or waveguide light. Another embodiment is the device formed using the thermal transfer element. In at least some instances, the thermal transfer element also includes a light-to-heat conversion (LTHC) layer that can convert light energy to heat energy to transfer the multicomponent transfer unit. The terms xe2x80x9cfirst operational layerxe2x80x9d and xe2x80x9csecond operational layerxe2x80x9d do not imply any order of the layers in the device or in the thermal transfer element or the proximity of the two layers to each other (i.e., there may be one or more layers between the first operational layer and the second operational layer.)
Another embodiment is a thermal transfer element that includes a substrate and a multicomponent transfer unit disposed on the substrate. The multicomponent transfer unit is configured and arranged to form, upon transfer to a receptor, a first operational layer and a second operational layer of an electronic component or an optical device. In at least some instances, this thermal transfer element may also have a LTHC layer.
A further embodiment is a thermal transfer element for forming an organic electroluminescent (OEL) device. This thermal transfer element includes a substrate and a multicomponent transfer unit that is configured and arranged to form, upon transfer to a receptor, at least two operational layers of the OEL device, such as, for example, an emitter layer and at least one electrode of the OEL device. Another embodiment is an OEL device formed using the thermal transfer element.
Yet another embodiment is a thermal transfer element for forming a field effect transistor. This thermal transfer element includes a substrate and a multicomponent transfer unit that is configured and arranged to form, upon transfer to a receptor, at least two operational layers of the field effect transistor, such as a gate insulating layer and a semiconducting layer. Another embodiment is a field effect transistor formed using the thermal transfer element.
Another embodiment is a thermal transfer element for forming a waveguide. This thermal transfer element includes a substrate and a multicomponent transfer unit that is configured and arranged to form, upon transfer to a receptor, at least two operational layers of the waveguide, such as at least one cladding layer and a core layer. Another embodiment is a waveguide formed using the thermal transfer element.
A further embodiment is a method of transferring a multicomponent transfer unit to a receptor to form a device, including contacting a receptor with a thermal transfer element having a substrate and a transfer layer. The transfer layer includes a multicomponent transfer unit. The thermal transfer element is selectively heated to transfer the multicomponent transfer unit to the receptor according to a pattern to form at least a first operational layer and a second operational layer of a device. In at least some instances, the thermal transfer element includes a LTHC layer between the substrate and the transfer layer. The thermal transfer element is illuminated with light according to the pattern and the light energy is converted by the LTHC layer to heat energy to selectively heat the thermal transfer element.
It will be recognized that thermal transfer elements can also be formed with a transfer unit that is configured and arranged to transfer a single layer. It will also be recognized that items, other than devices, may be formed by transferring either a multicomponent transfer unit or a single layer.
The above summary of the present invention is not intended to describe each disclosed embodiment or every implementation of the present invention. The Figures and the detailed description which follow more particularly exemplify these embodiments.